Conventionally, microfabrication has been carried out by lithography using photoresist compositions in the production of semiconductor devices. The microfabrication is a machining process in which a thin film of a photoresist composition is formed on a silicon wafer, active rays such as ultraviolet rays are radiated onto the film through a mask with a pattern of a semiconductor device followed by development, and the silicon wafer is etched using the obtained resist pattern as a protective film. However, in recent years, the integration density of semiconductor devices has been further increased and the active rays for use have a shorter wavelength and higher energy such as EUV rays (extreme ultraviolet rays, wavelength 13.5 nm), an electron beam, and X-rays, rather than i-rays (wavelength 365 nm), a KrF excimer laser (wavelength 248 nm), and an ArF excimer laser (wavelength 193 nm).
In the high-energy radiation resist film, a resist underlayer film used as an underlayer of the resist film has critical issues concerning adhesion to the resist, characteristics of resist shape, barrier performance for suppressing a passage of harmful substances between the underlayer (such as a substrate and an organic underlayer film) and the resist, performance of thin film formation (for example 30 nm or less), and characteristics of etching speed, as well as a decomposition product gas (out gas) that may be generated during the irradiation with high-energy radiation.
The exposure using such high-energy rays has a problem of contamination in a chamber by the outgassing due to the decomposition of a coated material.
Patent Documents 1, 2, and 3 disclose resist compositions that use an acid generator in an EUV resist to suppress outgassing for preventing such contamination. In Non-patent Document 1, there is a discussion concerning the reduction of outgassing in the resist underlayer film.